This invention relates to the general field of electrical connectors and is particularly concerned with outdoor mast lighting systems.
Mast lighting systems are well known and commonly support a light above the surface to be lighted with a long pole or mast. Masts are typically hollow, and may be round, square or of any selected cross-sectional shape which provides adequate stability. The mast may include a breakaway base at its lower end having an opening (or “handhole”) therein, through which the interior of the mast may be accessed by maintenance or installation personnel. The mast is typically mounted on a foundation of concrete or other suitable material set permanently into the ground and may be affixed to the foundation by a plurality of anchor bolts set into the foundation, which engage corresponding holes in the breakaway base.
Suspended at the top of the mast is an electrical component, commonly an electric light. In some applications, a cantilevered secondary mast or arm supports the light over a street or sidewalk. In other applications, a ring of high-intensity lamps may be supported radially around the distal end of the mast. The electrical component is electrically connected to a power source, generally in series with a number of other commonly powered mast units in a given area.
Power delivery to each light in a commonly powered system has been accomplished in a variety of ways. In one such system, the output of a master circuit breaker may be connected to an electric power cable which runs to the base of the mast. The power cable may connect to a fuse and surge arrestor assembly disposed within the hollow mast, which prevents current surges caused by lightning, voltage spikes or other anomalies from damaging the light fixture or the master circuit breaker. Access to the fuse and surge arrestor assembly is commonly provided by locating that assembly adjacent a handhole in the mast.
The performance of such a system is impaired by several shortcomings. Wire and cable attachments are generally made by splices, which are vulnerable to failure when tensile forces are applied to the connections.
In the event of an impact, the mast is often sheared off at the base and commonly comes to rest several yards from its original position. As is evident, the electrical circuit within the mast must be provided with means of disconnect which will allow the load side to separate from the line side by means of suitable tension applied to the load side conductors in the event a mast knockdown were to occur due to impact from a vehicle, thus preventing the feeder circuit being unearthed or broken; disrupting power to the rest of the circuit, which would be very important in the event of a nighttime accident; leaving broken or frayed electrical conductors exposed providing potential for electrocution to persons at the accident site; and energized electrical wires falling into traffic or the accident vehicle(s). In addition to these features, a fuse should be provided for protection of the load circuit, and in the event of a problem in the load circuit, the fuse would open, leaving the remainder of the lighting circuit energized.
Of particular importance, since this type of connector must be accessible for maintenance, is that the fuse be installed in such a manner that maintenance personnel are at no risk of electrical shock during fuse inspection or replacement. A further requirement for this application is that the connector be watertight, as certain conditions could occur, causing the connector to be submersed in flood water. Further, the connector should be easily assembled and serviced by technicians and capable of being capped on-site in the event of a mast knockdown.